Systems and methods of estimating optimal phases to use for individual antennas in an antenna array

Abstract

A method includes receiving a wireless communication signal indicating that a receiver is within a wireless-power-transmission range of a transmitter. In response to the receiving, the method further includes transmitting a plurality of radio frequency (RF) test signals using at least two test phases for a respective antenna. The method further includes receiving information identifying a first amount of power delivered to the receiver by a first RF test signal transmitted at a first of the at least two test phases, receiving information identifying a second amount of power delivered to the receiver by a second RF test signal transmitted at a second of the at least two test phases, and determining, based on the first and second amounts of power, an optimal phase for the respective antenna.

What is claimed is: 
     
       1. A non-transitory, computer-readable storage medium including instructions that, when executed by a wireless-power transmitter with an antenna array, cause the wireless-power transmitter to perform operations comprising:
 transmitting, via an antenna of the antenna array of the wireless-power transmitter, a set of radio frequency (RF) test signals, wherein each RF test signal in the set of RF test signals uses a distinct phase of a plurality of available phases for the antenna; 
 receiving, from a wireless-power receiver, information identifying respective amounts of power delivered to the wireless-power receiver by each RF test signal in the set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the wireless-power receiver, an optimal phase, wherein the optimal phase is a phase of the plurality of available phases for the antenna that delivers a greatest amount of power to the wireless-power receiver. 
 
     
     
       2. The non-transitory, computer-readable storage medium of  claim 1 , wherein the set of RF test signals includes at least two RF test signals. 
     
     
       3. The non-transitory, computer-readable storage medium of  claim 2 , wherein the set of RF test signals includes at least three RF test signals. 
     
     
       4. The non-transitory, computer-readable storage medium of  claim 1 , wherein the operations that the wireless-power transmitter is caused to perform further-comprise:
 transmitting, via the antenna of the antenna array, one or more RF power signals using the optimal phase of the plurality of available phases for the antenna to the wireless-power receiver, wherein the wireless-power receiver converts the one or more RF power signals into usable power. 
 
     
     
       5. The non-transitory, computer-readable medium of  claim 1 , wherein determining the optimal phase includes determining that an RF test signal in the set of RF test signals uses the optimal phase of the plurality of available phases for the antenna. 
     
     
       6. The non-transitory, computer-readable medium of  claim 1 , wherein determining the optimal phase comprises:
 determining an RF test signal in the set of RF test signals that delivers a greatest amount of power to the wireless-power receiver; 
 transmitting, via the antenna of the antenna array of the wireless-power transmitter, an additional set of RF test signals, wherein each RF test signal in the additional set of RF test signals uses another distinct phase of the plurality of available phases for the antenna, wherein each other distinct phase is separated from a respective phase used to transmit the RF test signal in the set of RF test signals by a respective phase increment; 
 receiving, from the wireless-power receiver, additional information identifying respective amounts of power delivered to the wireless-power receiver by each RF test signal in the additional set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the wireless-power receiver, the optimal phase. 
 
     
     
       7. The non-transitory, computer-readable medium of  claim 1 , wherein determining the optimal phase further comprises interpolating the optimal phase from the set of RF test signals. 
     
     
       8. The non-transitory, computer-readable medium of  claim 1 , wherein the wireless-power receiver is a first wireless-power receiver, the antenna of the antenna array is a first antenna, and the set of RF test signals is a first set of RF test signals, and wherein the instructions further cause the wireless-power transmitter to perform operations including:
 responsive to receiving, at the wireless-power transmitter, an additional wireless communication signal indicating that a second wireless-power receiver is within a wireless-power-transmission range of the wireless-power transmitter:
 transmitting, via a second antenna of the antenna array of the wireless-power transmitter, a second set of RF test signals, wherein each RF test signal in the second set of RF test signals uses a distinct phase of a plurality of available phases for the second antenna; 
 receiving, from the second wireless-power receiver, information identifying respective amounts of power delivered to the second wireless-power receiver by each RF test signal in the second set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the second wireless-power receiver, a respective optimal phase, wherein the respective optimal phase is a phase of the plurality of available phases for the second antenna that delivers a greatest amount of power to the second wireless-power receiver. 
 
 
     
     
       9. The non-transitory, computer-readable medium of  claim 1 , wherein a respective distinct phase of each RF test signal in the set of RF test signals is separated from another respective distinct phase of another test signal in the set of RF test signals by a predetermined phase interval. 
     
     
       10. The non-transitory, computer-readable medium of  claim 9 , wherein the predetermined phase interval corresponds to known characteristics of a pure sinusoidal wave. 
     
     
       11. The non-transitory, computer-readable medium of  claim 1 , wherein the operations that the wireless-power transmitter is caused to perform further comprise determining a location of the wireless-power receiver based on the optimal phase. 
     
     
       12. The non-transitory, computer-readable medium of  claim 1 , wherein the operations that the wireless-power transmitter is caused to perform further comprise, for each antenna of the antenna array of the wireless-power transmitter:
 transmitting a respective set of RF test signals, wherein each RF test signal in the respective set of RF test signals uses a distinct phase of a plurality of available phases for the respective antenna; 
 receiving, from the wireless-power receiver, information identifying respective amounts of power delivered to the wireless-power receiver by each RF test signal in the respective set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the wireless-power receiver, a respective optimal phase, wherein the respective optimal phase is a phase of the plurality of available phases that delivers a greatest amount of power to the wireless-power receiver. 
 
     
     
       13. The non-transitory, computer-readable medium of  claim 12 , wherein at least one optimal phase determined for a first antenna of the antenna array is distinct from another optimal phase determined for a second antenna of the antenna array. 
     
     
       14. The non-transitory, computer-readable medium of  claim 1 , wherein the plurality of available phases for the antenna to the wireless-power receiver includes at least 16 phases. 
     
     
       15. The non-transitory, computer-readable medium of  claim 14 , wherein the plurality of available phases for the antenna to the wireless-power receiver includes at least 64 phases. 
     
     
       16. A wireless-power transmitter, comprising:
 a wireless communications radio; 
 an antenna array; 
 one or more processors; and 
 memory storing one or more programs for execution by the one or more processors, the one or more programs including instructions for:
 transmitting, via an antenna of the antenna array of the wireless-power transmitter, a set of radio frequency (RF) test signals, wherein each RF test signal in the set of RF test signals uses a distinct phase of a plurality of available phases for the antenna; 
 receiving, from a wireless-power receiver, information identifying respective amounts of power delivered to the wireless-power receiver by each RF test signal in the set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the wireless-power receiver, an optimal phase, wherein the optimal phase is a phase of the plurality of available phases for the antenna that delivers a greatest amount of power to the wireless-power receiver. 
 
 
     
     
       17. The wireless-power transmitter of  claim 16 , wherein the set of RF test signals includes at least two RF test signals. 
     
     
       18. The wireless-power transmitter of  claim 17 , wherein the set of RF test signals includes at least three RF test signals. 
     
     
       19. The wireless-power transmitter of  claim 16 , the one or more programs further comprising instructions for:
 transmitting, via the antenna of the antenna array, one or more RF power signals using the optimal phase of the plurality of available phases for the antenna to the wireless-power receiver, wherein the wireless-power receiver converts the one or more RF power signals into usable power. 
 
     
     
       20. A method performed at a wireless-power transmitter that includes an antenna array, the method comprising:
 transmitting, via an antenna of the antenna array of the wireless-power transmitter, a set of radio frequency (RF) test signals, wherein each RF test signal in the set of RF test signals uses a distinct phase of a plurality of available phases for the antenna; 
 receiving, from a wireless-power receiver, information identifying respective amounts of power delivered to the wireless-power receiver by each RF test signal in the set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the wireless-power receiver, an optimal phase, wherein the optimal phase is a phase of the plurality of available phases for the antenna that delivers a greatest amount of power to the wireless-power receiver. 
 
     
     
       21. The non-transitory, computer-readable storage medium of  claim 1 , wherein no RF test signals in the set of RF test signals are transmitted using untested phases in the plurality of available phases for the antenna, and the optimal phase is one of the untested phases. 
     
     
       22. The wireless-power transmitter of  claim 16 , wherein no RF test signals in the set of RF test signals are transmitted using untested phases in the plurality of available phases for the antenna, and the optimal phase is one of the untested phases. 
     
     
       23. The method of  claim 20 , wherein no RF test signals in the set of RF test signals are transmitted using untested phases in the plurality of available phases, and the optimal phase is one of the untested phases. 
     
     
       24. The wireless-power transmitter of  claim 16 , wherein determining the optimal phase further comprises interpolating the optimal phase from respective distinct phases used to transmit each RF test signal in the set of RF test signals. 
     
     
       25. The wireless-power transmitter of  claim 16 , wherein the wireless-power receiver is a first wireless-power receiver, the antenna of the antenna array is a first antenna, and the set of RF test signals is a first set of RF test signals, and wherein the one or more programs further comprise instructions for:
 responsive to receiving, at the wireless-power transmitter, an additional wireless communication signal indicating that a second wireless-power receiver is within a wireless-power-transmission range of the wireless-power transmitter:
 transmitting, via a second antenna of the antenna array of the wireless-power transmitter, a second set of RF test signals, wherein each RF test signal in the second set of RF test signals uses a distinct phase of a plurality of available phases for the second antenna; 
 receiving, from the second wireless-power receiver, information identifying respective amounts of power delivered to the second wireless-power receiver by each RF test signal in the second set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the second wireless-power receiver, a respective optimal phase, wherein the respective optimal phase is a phase of the plurality of available phases for the second antenna that delivers a greatest amount of power to the second wireless-power receiver. 
 
 
     
     
       26. The wireless-power transmitter of  claim 16 , wherein a respective distinct phase of each RF test signal in the set of RF test signals is separated from another respective distinct phase of another test signal in the set of RF test signals by a predetermined phase interval. 
     
     
       27. The wireless-power transmitter of  claim 26 , wherein the predetermined phase interval corresponds to known characteristics of a pure sinusoidal wave. 
     
     
       28. The wireless-power transmitter of  claim 16 , wherein the one or more programs further comprise instructions for:
 for each antenna of the antenna array of the wireless-power transmitter:
 transmitting a respective set of RF test signals, wherein each RF test signal in the respective set of RF test signals uses a distinct phase of a plurality of available phases for the respective antenna; 
 receiving, from the wireless-power receiver, information identifying respective amounts of power delivered to the wireless-power receiver by each RF test signal in the respective set of RF test signals; and 
 determining, based on the respective amounts of power delivered to the wireless-power receiver, a respective optimal phase, wherein the respective optimal phase is a phase of the plurality of available phases that delivers a greatest amount of power to the wireless-power receiver. 
 
 
     
     
       29. The wireless-power transmitter of  claim 28 , wherein at least one optimal phase for a first antenna of the antenna array is distinct from another optimal phase determined for a second antenna of the antenna array.